Sunday, March 30, 2014

Rainfall Enables River Rises

Heavy rain overnight enabled local rivers and streams to rise and the result is minor to moderate flooding across Southern New England.  Here is a map of the rainfall totals from this system

NWS Boston Rainfall Reports
5.22" have fallen in Hope Valley, RI which is the highest amount I have found so far. See reports here.  Not surprisingly several rivers are near or above flood stage.  Yellow is near flood stage, orange is minor flooding, and red is moderate flooding.
Northeast River Forecast Center Current River Conditions
You can view river forecasts here .  The Yantic River in SE CT is the only river in moderate flood stage at the moment
NERFC Yantic River forecast 
The forecasts call for only minor flooding from here on out.  I did notice the rivers rose faster and higher than most of the forecast.  For example the Blackstone was forecast to rise to 6.6 ft yesterday afternoon, yet it is already at 8.3 feet.
NERFC Blackstone River forecast
The question now becomes how much more rain?  First of all let's look at the local surface chart
WPC Surface Analysis 11 am
A stalled boundary over the Cape separates raw temperatures from more spring like weather.  Here are the 1 PM temperatures (click to enlarge)
1 PM 2 m temperatures (image Weatherbell)
The precipitation has split in two batches.  One is just offshore MA up through Eastern Maine.  Another is pouring on the Mid Atlantic states
NWS Northeast Regional Radar 148 PM
The precip in the Mid Atlantic is driven by an impressive upper level system
12z NAM 500 mb vort valid 2 PM (image NCEP)
This shows up nicely on the water vapor satellite loop
GOES_East Water Vapor Satellite Loop 115 (NOAA)
This is not in a hurry to move so expect dry conditions throughout the afternoon.  Rain looks to move back in tonight and it could be heavy.  Here is 10 PM simulated radar
16z HRRR simulated radar 10 PM (image Weatherbell)
Due to the nature of the system it may be cold enough North and West of Worcester for freezing rain tomorrow AM.  For that reason a Winter Weather Advisory has been issued
03/30/14 NWS Headlines
That includes Northern Worcester Co, but the Flood Warning for the Assabet River takes precedent.  Monday looks miserable with temperatures in the upper 30's/low 40's.  That's all for now, another update tonight or tomorrow AM.

-Zack Green












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